A Corinth, Miss., man was arrested Wednesday night in connection with possibly contaminated letters sent to President Barack Obama and Sen. Roger Wicker (R-Miss.).
The FBI arrested Paul Kevin Curtis at his home, the U. S. Department of Justice said in a statement that also detailed that a third letter was sent to a Mississippi justice official.
The letters to Wicker and Obama – discovered Tuesday – were stopped at a government mail-screening facility after initial tests indicated the presence of the deadly poison ricin.
Because initial tests can be "inconsistent," the envelopes have been sent off for additional tests, an FBI statement said. The FBI does not expect to receive results from the tests until Thursday (April 18), federal law enforcement sources told CNN.
The letters read: "To see a wrong and not expose it, is to become a silent partner to its continuance."
They were signed "I am KC and I approve this message," a source said.
Reports of suspicious packages and envelopes also came into two Senate office buildings late Wednesday morning. Capitol Police evacuated the first floor of the Hart Senate Office Building for more than an hour.
In reaction to the poison-letter scare in Washington, Memphis Mayor A C Wharton Jr. on Wednesday issued the following statement:
"We are grateful that, to this point, these letters have been intercepted before causing injury to anyone. While it has not been confirmed that the letters originated from Memphis, it is regrettable that our name is connected in any way with this heinous act. Local law enforcement officials have been in contact with the investigating agency, the FBI, and stand ready to cooperate as needed."
Sadie Holland, a judge in Lee County, Miss., told CNN Wednesday night that she received an envelope with a suspicious substance and a letter similar to the ones sent to the offices of Obama and Wicker.
Last Wednesday, the judge received and opened a typewritten letter – postmarked from Memphis, without a return address – that included "suspicious content," Lee County Sheriff Jim Johnson told reporters. The letter had "great consistencies and similarities" to the letters sent to Obama and Wicker, he said. Investigators were testing the contents of the letter to determine whether ricin was inside, he said.
Holland told CNN the letter originally tested negative for ricin but was being retested Wednesday. Local authorities were awaiting the test results to determine whether to file state charges, Johnson said.
"The letter was handled, the chemical was handled by several different individuals in our justice court system," Johnson said, but added that "we do not have any reason to believe that anyone's life is in danger."
Investigators are trying to determine whether suspicious letters found at Senate offices elsewhere in the country came from the same source, federal law enforcement sources said.
In a statement issued Wednesday, the FBI said it has no indication of a connection between the tainted letters and Monday's bombings at the finish line of the Boston Marathon.
White House spokesman Jay Carney said the president had been briefed on the letters.
Wicker has been assigned a protective detail, according to a law enforcement source.
After the arrest was announced Wednesday night, Wicker released a statement thanking "the men and women of the FBI and U.S. Capitol Police for their professionalism and decisive action in keeping our family and staff safe from harm." His offices in Mississippi and Washington "remain open for business to all Mississippians," Wicker said in the statement.
A previous ricin scare hit the Capitol in 2004, when tests identified it in a letter in a Senate mailroom that served then-Majority Leader and Bill Frist's office. The discovery forced 16 employees to go through decontamination procedures, but no one reported any ill effects afterward, said Frist, a Republican who represented Tennessee
(CNN's Joe Johns, Jessica Yellin, Dana Bash, Tom Cohen, Terry Frieden, Deanna Hackney, Elwyn Lopez, Lisa Desjardins and Rachel Streitfeld contributed to this report.)